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AZURITE MINE REMOVAL ACTION OVERVIEW. Dustin G. Wasley, PE, Principal – CES 2013 American Society of Mining and Reclamation Conference Laramie, Wyoming -- June 6, 2012. Azurite Mine Overview. Abandoned Underground Gold Mine, Located in North-Central WA on USFS-Administered Land

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Azurite mine removal action overview

AZURITE MINEREMOVAL ACTION OVERVIEW

Dustin G. Wasley, PE, Principal – CES

2013 American Society of Mining and Reclamation Conference

Laramie, Wyoming -- June 6, 2012


Azurite mine overview
Azurite Mine Overview

  • Abandoned Underground Gold Mine, Located in North-Central WA on USFS-Administered Land

  • Northwest of Mazama, Near Harts Pass Recreation Area & Pacific Crest Trail

  • Remote with Poor Access, Steep Terrain

  • Several RTE Species – Aquatic and Terrestrial

  • Inventoried Roadless/Non-Motorized Management Area

  • High Value for Potential Wilderness Area in Future


Azurite mine location
Azurite Mine Location

AZURITE MINE

MAZAMA


OVERVIEW OF AZURITE MINE FROM TINSON ADIT

TAILINGS

~55,000 CY

~4 acres

CADY PASS

MILL AREA

WASTE ROCK

~22,000 CY

~1 acre

WENATCHEE ADIT

MILL CREEK

OFFICE BUILDING


Azurite mine early history
Azurite Mine – Early History

  • 1915 – 31 Claims Staked

  • 1916 – Azurite Copper Company (renamed Azurite Gold)

  • 1918 to 1931 – Underground Development

  • 1934 – ASARCO Leased Mine

  • 1934 to 1936 – 100 TPD Mill and Infrastructure

  • 1936 to 1942 –Development, Production

    • ~73,000 tons @ 0.38 opt gold

  • 1942 – ASARCO Removes Equipment



Azurite mine recent history
Azurite Mine – Recent History

  • 1995 – Discovery Assessment (USFS)

  • 2002 – IAM Open File Report (WA DNR)

  • 2004/2005 – CERCLA Site Inspection (USFS/CES)

  • 2005 – Reprocessing Study (USFS/CES); – PRP Report (USFS)

  • 2006 to 2008 – EE/CA & Risk Assessment (ASARCO/MFG)

  • 2008 – ASARCO Settlement with USFS~$5.5M

  • 2007 to 2010 – Data Gaps/Removal Design (USFS/CES)

  • 2011 – Removal Action Activities


Final removal action alternative
Final Removal Action Alternative

  • Access Road Improvements / Bridge Replacement (2010)

  • Temporary Access Road Across Mill Creek (2011)

  • Mill Creek Diversion Away from Waste Rock Pile (2011)

  • Onsite Covered Repository (2011)

    • Reinforced Stabilized Slope/Repository Toe Berm

    • Waste Rock and Mill Area Soil Blended with Tailings

    • Multi-Layer Cover, HDPE Membrane, and Talus/Rock Cover

  • Physical Hazard Closures (2011)

  • Revegetation (2011) – USFS Lead


Construction challenges
Construction Challenges

  • Weather Conditions (rain, snow, heat)


Construction challenges1
Construction Challenges

  • Weather Conditions (rain, snow, heat)

  • Typical Construction Window (late June – early October)

  • Steep Slopes / Difficult Terrain

  • Limited Onsite Staging Areas

  • All Borrow Material from Onsite

  • Remote Access/Logistics/Communication


2011 removal action summary
2011 Removal Action Summary

  • Turnkey “Design/Build” Contract Structure

    • CES – Prime Contractor

    • Palm Construction – Main Subcontractor (Local)

  • Mobilization – July 11, 2011 – 3 weeks late (weather)

  • Continuous Work Schedule, CES and Subs

  • Demobilization – September 26, 2011 – 1 week early


OVERVIEW OF AZURITE MINE REMOVAL ACTION

TAILINGS PILE

Contour with WR/Mill Soils, and Construct Repository

STABILIZED SLOPE

Construct to retain Repository

WASTE ROCK

Excavate and Haul to Repository

MILL AREA

Excavate and Haul to Repository


Camp equipment and manpower
Camp, Equipment and Manpower

  • Remote Camp (internet, phones, running water, flushing toilets, showers, washer/dryer, cook, tents/campers)

  • 3 Excavators

  • 2 Loaders

  • 3 Dozers

  • 2 Off-Road, Articulated Haul Trucks

  • Roller Compactor, Water Truck, Misc. Work Trucks

  • Bear Proof Storage Containers

  • Manpower – 10 to 20 (Palm/Subs) / 1 to 3 (CES)


Erosion and sediment control
Erosion and Sediment Control

  • Run-On Ditches

    • Waste Rock / Tailings

  • Silt Fence

    • Borrow Area / Waste Rock

  • Filter Berms

    • Borrow Area / Waste Rock

  • Sedimentation Pond

    • Tailings / Repository


Mill creek crossing and diversion
Mill Creek Crossing and Diversion

  • Access Waste Rock Pile, and Transport to Repository

  • Three, 48-inch CMPs

  • Temporarily Divert Mill Creek Away From Waste Rock Pile



Borrow area development
Borrow Area Development

  • Onsite Source for Screening / 3 Products

  • 2-inch minus

    • Stabilized Slope Fill, Road Bed/Base, Fill Material

    • 40,000+ cubic yards used, more remains onsite

  • 2-inch to 36-inch

    • Repository cover, rocked diversion ditches

    • ~20,000 cubic yards

  • 36-inch plus

    • Misc. Placement, armoring




Underground working closures
Underground Working Closures

  • Planned for 5 Closures (4 Adits / 1 Vent)

  • Pre-Cut Steel and Culverts Delivered to Site

  • Final Onsite Fabrication

  • Installation with Helicopter and Onsite Welder

  • 4 Closures

    • Burnham, Tinson, and Discovery Adits

    • Discovery Vent

  • Wenatchee Adit

    • Collapsed - No Bat Gate Installed


Reinforced stabilized slope
Reinforced Stabilized Slope

  • Designed to Stabilize/Retain the Repository

  • Original Design was 15-feet (H) x 15-feet (W) – 12 lifts

  • Final Layout was 22-feet (H) x 25-feet (W) – 17 lifts

    • Competent Soil Deeper Than Planned

    • Increased Quantities For Borrow Material/Geogrid

  • Onsite QA/QC Testing – All Final Tests Met Compaction Requirements (95% of Proctor)

  • 23 days to build

    • Bottom lifts ~ 1.5 days to complete

    • Upper lifts ~ 1 day to complete









Waste rock excavation and placement
Waste Rock Excavation and Placement

  • Design Estimate was 22,000 bcy of Waste Rock

  • Risk Assessment Cleanup Goal – 104 mg/kg Total Arsenic

  • Revised Cleanup Goal – 204 mg/kg Total Arsenic

    • Additional Background Soil Sampling

    • Used MTCA Stat 3.0 to Calculate Natural Background

  • In-Field Screening with Niton XRF (RPDs ≤ 33%)

  • Final Quantities ~ 16,500 bcy






Onsite repository
Onsite Repository

  • Overall Slope = 2.5:1

  • Reinforced Slope and Berm to Stabilize Repository

  • Waste Rock Blended with Tailings to Achieve Slope

  • In-sloped Benches Every 9 Vertical Feet

  • Repository Cover (Multi-Layer)

    • Talus/Rock Cover – Top

    • Geogrid

    • 12-oz Nonwoven Geotextile

    • 40-mil HDPE Membrane

    • 12-oz Nonwoven Geotextile

    • Waste Rock/Tailings – Bottom



















Summary
Summary

  • Completed 4 Weeks Ahead of Schedule

  • Field Changes Easily Made with Continuous Oversight & Communication

  • No Health/Safety Concerns

  • 3-Years of Long-term O&M Inspections, & Monitoring

  • RA Cost - $2.5M Capital



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